brittone2
10-29-2006, 12:29 AM
http://bmj.bmjjournals.com/cgi/content/full/333/7574/912
Interesting highlights:
The second problem is either the absence of evidence or the absence of convincing evidence on most of the effects at the centre of campaign objectives (table 2). In children under 2 years inactivated vaccines had the same field efficacy as placebo,8 and in healthy people under 65 vaccination did not affect hospital stay, time off work, or death from influenza and its complications.9 Reviews found no evidence of an effect in patients with asthma or cystic fibrosis, but inactivated vaccines reduced the incidence of exacerbations after three to four weeks by 39% in those with chronic obstructive pulmonary disease.12 13 19 All reviewers reported small data sets (such as 180 people with chronic obstructive pulmonary disease13), which may explain the lack of demonstrable effect.
The third problem is the small and heterogeneous dataset on the safety of inactivated vaccines, which is surprising given their longstanding and widespread use. A Cochrane Database Systematic Review found only one old trial with data from 35 participants aged 12-28 months.8 In the general population of elderly people, despite a dataset of several million observations, safety was only reported in five randomised controlled trials (2963 observations in total) on local and systemic adverse events seen within a week of giving parenteral inactivated vaccine.11 Although there appears to be no evidence that annual revaccination is harmful, such a lack of knowledge is surprising.
Interesting highlights:
The second problem is either the absence of evidence or the absence of convincing evidence on most of the effects at the centre of campaign objectives (table 2). In children under 2 years inactivated vaccines had the same field efficacy as placebo,8 and in healthy people under 65 vaccination did not affect hospital stay, time off work, or death from influenza and its complications.9 Reviews found no evidence of an effect in patients with asthma or cystic fibrosis, but inactivated vaccines reduced the incidence of exacerbations after three to four weeks by 39% in those with chronic obstructive pulmonary disease.12 13 19 All reviewers reported small data sets (such as 180 people with chronic obstructive pulmonary disease13), which may explain the lack of demonstrable effect.
The third problem is the small and heterogeneous dataset on the safety of inactivated vaccines, which is surprising given their longstanding and widespread use. A Cochrane Database Systematic Review found only one old trial with data from 35 participants aged 12-28 months.8 In the general population of elderly people, despite a dataset of several million observations, safety was only reported in five randomised controlled trials (2963 observations in total) on local and systemic adverse events seen within a week of giving parenteral inactivated vaccine.11 Although there appears to be no evidence that annual revaccination is harmful, such a lack of knowledge is surprising.